Does Memory Impairment Exclude a Diagnosis of OCD After Traumatic Brain Injury?

The first case has been reported in greater depth elsewhere² and is presented for comparison only. A 27-year-old man presented with OCD with severe TBI, after a road-traffic collision 51/2 years earlier. He presented with clear obsessions and compulsions. His Florida Obsessive Compulsive Inventory (FOCI)⁵ provided further evidence of obsessions and compulsion. There was no premorbid history of psychiatric illness. A CT of the brain showed a fracture of the left parietal bone extending into the floor of the anterior fossa, a left frontal contusion, and a basal skull fracture. The remainder of the brain was reported as normal. Cognitive assessment revealed superior general intellectual ability, normal memory, but subtle impairment of executive function, in particular, set-shifting (Trails). Indeed, the patient reported often remaining overly focused on one aspect of a situation to avoid possible distraction (poor set-shifting). Uncertainty when recalling information resulted in repetitions, when objectively memory performance was robust.

The second case is a 56-year-old man with severe TBI after a fall, seen 7 years post-TBI for repeat neuropsychological testing. He had no premorbid psychiatric illnesses. He presented with disinhibited behavior, severe memory impairment, and being very rooted in behavioral patterns. He hoarded numerous objects in his pockets, becoming anxious when having to empty his pockets—behavior that appears to resemble obsessions and compulsions. Whereas the FOCI⁵ showed moderately elevated scores, the performance was clearly a reflection of poor memory. Cognitive assessment revealed average-to-high average general intellectual ability. There were subtle indications of executive dysfunction in the area of set-shifting (Trails). Very significant impairment of memory was present. Neuro-imaging showed contusions to the orbito-frontal cortex bilaterally, large hematomas and contusions of the left occipital and temporal lobes and lateral and ventral-temporal lobe of the left hemisphere.

The cases reported here unsurprisingly both had executive dysfunction, very common in TBI. Memory may be a more useful function to consider, as it appears to function as a conduit between obsessions and compulsions in OCD. TBI patients with memory impairment may present with repetitive behaviors mirroring compulsions, which may actually often represent their strategy for preventing memory failure, as opposed to a response to obsessions. Where this is the case in patients with TBI, a diagnosis of OCD should be questioned.